1. Field of the Invention
The present invention relates to a suspended ceiling system and more particularly to a connector means for connecting cross-runner members to main runner members in a suspended ceiling grid system for acoustical tile or the like.
2. Description of the Prior Art
Suspended ceiling systems are extensively used throughout the construction industry, both in new building construction and in the renovation of older buildings. This type of ceiling consists of a grid-like supporting base which is suspended from the true ceiling and which supports a layer of ceiling panels, typically acoustical tile. This suspended grid also oftentimes serves as a support base for lighting fixtures and heating and air conditioning outlet ducts.
The grid itself is formed by two sets of beams joined together, the "main runners" and the "cross runners". The main runners consist of long beam segments, parallel to one another, each typically extending across the length of the ceiling. Where this distance is longer than the individual length of a beam segment, a number of such segments are spliced together to create one continuous longitudinal beam. In contrast, the cross runners, while also parallel to one another, form discontinuous beams which typically span only the distance between the main runners. The grid system is suspended from the true ceiling using wires or other similar means attached to the man runners.
Several different systems for the attachment of the cross runners to the main runners are known to the art. They can generally be divided into two groups: the unitary connectors and the separate or piece connectors. Unitary connectors have the connector pieces integrally formed as part of the cross runner. Such a construction is shown in U.S. Pat. No. 3,979,874 to Cubbler, Jr., et al. The end portions of the cross runners are provided with vertical tabs which are inserted into slots formed in the web portion of the main runners. U.S. Pat. Nos. 3,565,474 to Stumbo, et al., and 4,161,856 to Brown, et al., are similar, with both providing tongues which project from the ends of the cross members. In Stumbo, et al., the tongue is integrally formed with the beam webbing, while Brown, et al., provides rivets for the attachment of the tongue portion.
A variety of separate connector pieces are also disclosed in the prior art. U.S. Pat. No. 3,385,021 to Nys provides a connecting plate that is received by grooves in the cross member flanges (top and bottom). The plate is provided with a projecting member which is received by a slot in the main runner. U.S. Pat. No. 3,093,221 to Purdy provides a connecting plate that clips to the cross runner and a spring nose that enters a hole in the main runner. U.S. Pat. No. 3,677,589 to Roles provides an installation clip which connects with the cross member using mating slots, and connects with the main runner utilizing a concave engaging portion. Finally, U.S. Pat. No. 3,596,425 to Kodaras provides a clip member which is received by slots in a specially designed main runner. The clip member then attaches to two cross runners using locking tabs.
The great utility, and in fact, popularity, of these ceiling grid suspension systems is directly related to the ease of their on-site installation. In commercial sidings particularly, not only is the facility of installation important, but much consideration is also given to the adaptability of the system to differing ceiling constructions and the amount of time required for installation.
Often in the prior art, the simplest and quickest connections were provided by the integral connectors. These, however, have a drawback that they are more expensive to manufacture. The separate connector assemblies, while less expensive to manufacture, often had the problem of poor mechanical connections. Unless locking tabs or other bendable connectors were used, looseness often existed in the connection.